1. Field of the Invention
This invention is directed to light fixtures, in general, and, more particularly, to a light fixture wherein a conventional incandescent light source is readily converted to a fluorescent, metal halide, high pressure sodium or similar light source which uses a ballast.
2. Prior Art
There are many types of light fixtures which are known in the art. These include recessed fixtures, surface mounted fixtures, track-light fixtures and the like. Most of the known light fixtures use incandescent light sources therein. However, incandescent light sources have a short life and are inefficient. The number of lumens generated per electrical watt consumed is not economical and is generally in the area of 14 to 17 lumens per watt.
In addition, these types of light sources generally use a thin filament which glows when heated by electrical power, and tends to burn out or break rather easily.
Also, incandescent light sources tend to generate a large amount of heat which is given off into the surrounding area. This has the secondary shortcoming of producing heat in many places where excessive heat is not desired. Consequently, it becomes necessary to use air conditioning equipment or the like to eliminate this unwanted heat. Consequently, incandescent light sources tend to be energy consumers and wasters.
Several types of alternative light sources are known in the art. For example, fluorescent, high pressure sodium and metal halide lamps and the like are typical. These light sources generally tend to operate quite efficiently and provide 50 to 120 lumens per watt. The lower wattages do not, as a rule, produce excess heat during operation.
However, these alternative light sources are normally not interchangeable with incandescent lamps or bulbs. For one thing, the different light sources may have different couplings, as is the case with fluorescent. The "Edison-base" coupling which is common on the ordinary incandescent lamp and light fixture will not accept standard fluorescent fittings. Although single ended high pressure sodium and metal halide lamps are available and can be screwed into an Edison-base socket, they cannot be successfully operated because all the arc discharge lamps covered under this invention require a ballast to operate the lamp. Since the ballast may be relatively large, it usually cannot be mounted within the interior of the fixture.
In essence, the ballast must be used to deliver the proper current to the particular light source. The wattage of lamp, lamp type and line voltage will dictate the specific ballast design to match the lamp.
Normally, line voltage is 120 volts or 240 volts. However, other voltages may be encountered. Therefore, a specific ballast must be used to drive a specific lamp.
In order to convert an existing inefficient incandescent lighting system to a more efficient light source, it has been necessary to replace the existing lighting fixture with a totally new lighting fixture that incorporates the proper socket configuration and ballast assembly in a new fixture.
Certain retrofit light fixtures were developed which included ballasts built right into the fixture itself or an attached housing. These light fixtures, however, required an ample and substantial amount of space within the existing fixture to house the ballast and socket assemblies.
Consequently, it is highly desirable to develop ligh fixtures which permit these alternative light sources to be retrofitted into existing electrical system hardware efficiently and economically.